Hints support

Hi all,
currently Calcite does not support hints. Since usually hints are expressed
as multi-line comment after SELECT keyword followed by the plus sign [1],
Calcite ignores them as all others comments.It can be useful if Calcite
will provide functionality to store hints and allow source system to use
them during planning / execution time.
Any thoughts?
[1] https://docs.oracle.com/cd/B12037_01/server.101/b10752/hintsref.htm
Kind regards,
Arina